The present invention relates to an isolation work station suitable for providing an ultra clean work environment for the production of sterile products, drug manufacturing operations, and the like.
Work station isolators are known which comprise a generally rectangular enclosure having a glass front wall which mounts one or two flexible gloves for permitting a technician to reach through the wall and into the enclosure to perform work tasks therein and while being isolated from the environment within the enclosure. Also, in order to minimize the chances for contamination, isolators of this type commonly provide a filtered, laminar air flow downwardly through the enclosure, so as to prevent airborne contaminants from coming into contact with the sterile products being processed in the enclosure.
In the case of many manufacturing or assembly operations, it is necessary to completely sterilize the interior of the isolator between manufacturing operations, so as to prevent product contamination. As one example, the Food and Drug Administration (FDA) currently recommends that all medical and surgical products be sterilized so as to achieve a live organism count of less than one part per million in the enclosure. In order to provide such sterilization, steam or ethylene oxide treatments have been suggested, but more conventionally, the sterilization is accomplished by vaporized hydrogen peroxide which is circulated through the enclosure for a period of time, such as 10-15 minutes. A generator capable of generating vaporized hydrogen peroxide for this purpose is disclosed, for example, in U.S. Pat. Nos. 4,863,688 and 4,935,371, and such a generator is manufactured by the American Sterilizer Company of Erie, Penn. as Model No. VHP1000.
After sterilization is complete, it is necessary to then flush the residual hydrogen peroxide from the isolator, and this is typically accomplished by passing an airstream through the isolator while bleeding off a parallel stream which is passed through a granular gas type filter which contains a catalyst for degrading the residual hydrogen peroxide into moisture and oxygen, and which is located in the vaporized hydrogen peroxide generator. Since the hydrogen peroxide is absorbed by plastic, and other materials which are normally present in the isolator, it takes a significant time, typically 24 hours, for these materials to offgas the hydrogen peroxide and for the isolator to reach the required levels to permit the isolator to be reused with other products.
It is an object of the present invention to provide a work station isolator of the described type which has the capability of rapidly and efficiently purging the residual hydrogen peroxide from the isolator after the sterilization procedure.
It is a further object of the present invention to provide an isolation work station of the described type which, during the normal cycle of operation, efficiently degrades any residual hydrogen peroxide which may be released from the components of the work station after the purging cycle is completed.